Efficient printer control electronics

ABSTRACT

An apparatus (such as a printer) including a combination engine controller circuit board having a integrated circuit (IC) chip configured to process (format) incoming data as well as to control the operations of the apparatus is disclosed. The IC chip is adapted to receive and process data as well as to control the operations of the apparatus. For this reason, the IC chip is referred to as a combined controller IC.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/419,815, filed Apr. 7, 2009, which is a continuation of U.S.application Ser No. 10/655,418, filed Sep. 3, 2003, the contents of bothof which are hereby incorporated by reference in their entirety.

BACKGROUND

The present invention relates to application specific integrated circuit(ASICS), and more particularly, to ASICS for controlling operations ofvarious appliances such as printers.

Many electronic appliances include a processor, a control processor, tocontrol operations of various components of the appliance. Someappliances include a second processor, a data processor, to processrelatively large amounts of relatively complex data received by theappliance, generated by the appliance, or both. Further, theseprocessors are often attached to its own printed circuit boards (PCBS).For example, current generation printers typically have thisconfiguration.

FIG. 1A is a simplified schematic illustration of an appliance 10 (forexample, a laser printer 10) having a prior art configuration. FIG. 1Bis a more detailed schematic illustration of portions of the appliance10. Referring to FIGS. 1A and 1B, the printer 10 receives complex data22 from a host computer 20. The data 22 is analyzed and formatted by adata processor 32 on a formatter board 30. The formatted data iscommunicated to a control processor 42 on an engine controller board 40.The two processors 32 and 42 typically communicate via a serialinterface 41.

The data processor 32 is typically a high performance ASIC (applicationspecific integrated circuit) 32 having a number of portions integratedwithin the ASIC 32. For example, the ASIC 32 includes a processing core36 and its own internal memory 34 such as DRAM (dynamic random accessmemory) 34. Further, the ASIC 32 may include other integrated portions38 not illustrated in detail. The ASIC 32 operates at a relatively highspeed, for example, 100 MHz, to perform complex tasks such as formattingthe complex data 22 in preparation for printing by the printer 10. Theformatted data is sent to the control processor 42 for printing.

The ASIC 32 is connected to an external memory 39 such as flash memory39 containing instructions and various parameters used for theoperations of the ASIC 32. Flash memory technology is known in the artas non-volatile memory that can be erased, reprogrammed, or updated. Byupdating the flash memory 39, the operations of the data processor 32can be updated to accommodate updates or changes in technology.

The control processor 42 is typically a low performance microcontroller(compared to the data processor 32). The control processor 42 includesROM (read only memory) 43 to permanently store instructions for itsprocessor 46 and may include additional memory elements such as SRAM 44(static random access memory) for its operation. The control processor42 receives page formatting information

The control processor 42 receives page formatting information from thedata processor 32 and controls various electro-mechanical components(represented here as a box 50) to generate a printed page in accordancewith the formatted data received from the data processor 32. The controlprocessor 42 includes analog-to-digital converters (ADC) anddigital-to-analog converters (DAC), collectively illustrated as ADAC 48.The ADAC 48 are connected to, communicate with, and control analogcomponents 49 on the engine controller board 40. The analog components49 are connected to, communicate with, and control theelectro-mechanical components 50 of the printer 10. Theelectro-mechanical components 50 include, for example only, fuser,stepper motor, laser scanner, voltage supply, printer engine, pagetimer, drum, and paper sensors.

The current design suffers from a number of disadvantages. For example,two printed circuit boards 30 and 40 introduce complexity and requiresignificant area and space within the printer 10. The two processors 32and 42 often require different voltage levels requiring separate powersupply circuitry for each of the processors 32 and 42. The instructionsfor the control processor 42 are embedded in the read only memory (ROM)43. Accordingly, it cannot be updated after the initial programming.Since the ROM 43 cannot be updated after the initial programming,printer specific control processors 42 are programmed and stocked foreach type and model of printer. The control processors 42 cannot beshared between differing models of the printers. In fact, even for thesame model printers, differently programmed control processors 42 arestocked to accommodate printers shipped to differing areas. For example,different parameter settings, for example temperature settings forfusers, are needed for printers shipped to tropical regions compared toprinters shipped to arctic regions.

Accordingly, there remains a need for a method and apparatus toeliminating or alleviate these disadvantages of the current appliances.

SUMMARY

The need is met by the present invention. According to a firstembodiment of the present invention, an integrated circuit (IC) chipincludes a processing core adapted to process digital data andcontroller circuits adapted to communicate with analog componentscontrol electro-mechanical components.

In a second embodiment of the present invention, an apparatus includes acombination engine controller board and memory connected to thecombination engine controller board. The combination engine controllerboard includes an integrated circuit (IC) adapted to receive and processdata, the IC having a processing core and controller circuits adapted tocontrol electro-mechanical components. The memory includes instructionsfor the IC. The instructions, when executed by the IC, cause the IC toprocess the received data and to control operations of theelectro-mechanical components.

Other aspects and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a simplified schematic view of a prior art apparatus;

FIG. 1B is a more detailed schematic illustration of portions of theapparatus of FIG. 1A;

FIG. 2A is a simplified schematic view of an apparatus according to oneembodiment of the present invention;

FIG. 2B is a more schematic illustration of portions of the apparatus ofFIG. 2A; and

FIG. 3 illustrates a timing diagram.

DETAILED DESCRIPTION

The present invention will now be described with reference to FIGS. 2Athrough 2B, which illustrate a sample embodiment of the presentinvention. As illustrated in the Figures, relative sizes of variousportions, structures, or any combination of these are exaggerated forillustrative purposes and, thus, are provided to illustrate the generalstructures of the present invention.

As shown in the Figures for the purposes of illustration, one embodimentof the present invention is exemplified by an apparatus, for example aprinter for printing data received from a host computer. The printerincludes a combination engine controller board and variouselectro-mechanical components to accomplish its printing function. Thecombination engine controller board includes an ASIC chip and connectedflash memory. Here, the ASIC chip formats the received data. Further,the ASIC chip is configured to include controller circuits adapted tocontrol the electro-mechanical components of the printer. For thisreason, the ASIC is also referred to as a combined controller ASIC.

Because the ASIC chip performs both the formatting function and thecontrol function, a second processor such as the control processor 42 ofFIGS. 1A and 1B is not needed. Indeed, the need for the enginecontroller board 40 is eliminated. Thus, the printer is simplified,costs reduced, and reliability increased.

Furthermore, operations of the combined control ASIC is stored in aflash memory that can be updated with instructions and with operationalparameters.

Accordingly, there is no need to stock printer-specific processors ormemory. The combined control ASIC part as well as the flash memory canbe shared between printer models. The flash memory need only beprogrammed differently for different models or for different regionalsettings even with the same model. Consequently, significantmanufacturing time and cost savings can be realized.

FIG. 2A is a simplified schematic view of an apparatus 100 according toone embodiment of the present invention illustrated as a printer 100.FIG. 2B is a more schematic illustration of portions of the apparatus100 of FIG. 2A. The printer 100 of FIGS. 2A and 2B includes componentsthat are similar to corresponding components of the printer 10 of FIGS.1A and 1B. For convenience, components in FIGS. 2A and 2B that aresimilar to corresponding components in FIGS. 1A and 1B are assigned thesame reference numbers. Different components are assigned differentreference numbers.

Referring to FIGS. 2A and 2B, the printer 100 includes a combinationengine controller board 130 including in integrated circuit (IC) 132adapted to receive data 22 from a host computer 20, the data forprinting by the printer 100. In the illustrated embodiment, the IC 132is an application specific integrated circuit (ASIC). It is known in theindustry that ASICS, in general, can be configured to include variousportions, each portion having different electronic circuits and servingfunctions different than the other portions of the same ASIC.

Here, the ASIC 132 is configured to process (to format in this example)the received data 22. Further, the ASIC 132 is configured to includecontroller circuits 140 adapted to control the electro-mechanicalcomponents 50 of the printer 100. For this reason, the ASIC is alsoreferred to as a combined controller ASIC 132. Instructions for thecombined controller ASIC 132 to perform its functions can reside withinthe combined controller ASIC 132. Alternatively, the instructions forthe combined controller ASIC 132 can be stored in memory 139 connectedto but external to the combined controller ASIC 132. The external memory139 is often a flash type memory which is non-volatile, but can beerased and reprogrammed. The instructions are often referred to asfirmware.

The combined controller ASIC 132 includes a processor core 136 and itsinternal memory 138 such as DRAM 34. The combined controller ASIC 132includes other portions for various functions such as communicationinterface, codec (coder-decoder circuits), and DMA (direct memoryaccess) circuits. These other portions are illustrated in FIG. 2B as asingle box 138. All these portions are connected to an internal bus 131for communications.

The controller circuits 140 include a bus bridge 141 which bridges databetween the internal bus 131 and other parts of the controller circuits140. The bus bridge 141 attaches the controller circuits 140 to on-chipASIC backplane. The controller circuits 140 also include a fusercontroller 142, a stepper motor controller 144, a laser scannercontroller 146, a voltage controller 148, general purpose input andoutput (GPIO) circuits 150, interrupt controller 152, page timer 154,and an analog-to-digital interface 156. Each of these parts of thecontrol circuits 140 are discussed in more detail below.

The control circuits 140 are connected to, communicate with, and controlanalog components 49 on the combined engine controller board 130. Theanalog components 49 are connected to, communicate with, and control theelectro-mechanical components 50 of the printer 10. Theelectro-mechanical components 50 include, for example only, fuser,stepper motor, laser scanner, voltage supply and control circuits,printer engine, sensors and interrupt generators, page timer, drum,paper sensors, and solenoids. Further, some analog components such as,for example only, analog-to-digital components, can be integrated in theASIC 132.

Fuser Controller 142

The fuser controller 142 is used to ramp and maintain the temperature ofthe fuser (a part of the electro-mechanical component 50 of the printer100). To prevent a fire hazard, the fuser controller 142 is servicedwithin 150 milliseconds (ms) of an interrupt request, or the fusercontroller 142 is automatically disabled and reports a timeout error.The fuser controller 142 uses pulse width modulated (PWM) signal toswitch a triac (of the electro-mechanical component 50 of the printer100) that controls a 220/110 volt AC heating element.

An interrupt is generated when the fuser controller 142 is ready for anupdated PWM value. If a “ready” bit is not cleared in about 150 ms, thenthe fuser controller 142 shuts down the PWM control as a safetyprecaution.

The fuser controller 142 includes a fuser control register oneembodiment of which is illustrated below (TABLE 1) as a 32-bit wideregister having several significant bits. This register controls thestate of a fuser power relay (an additional safety interlock within theelectro-mechanical component 50 of the printer 100). The relay isenabled to pass power to the triac. The fuser power relay should beenabled prior to enabling the fuser enable pulse-width-modulated (PWD)output, and should remain enabled while fuser enable output signal/bit(FSRE) is active. An enable bit enables a fuser ready output (triac PWMcontrol).

TABLE 1 Fuser Control Register (FCR) Read/Write 0x010500C0 31 30 29 2827 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E RDefault X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 0R: Fuser safety Ready enable (1 = enable relay, 0 = disable relay) E:Enable fuser enable (FSRE) output (1 = enabled)

The fuser controller 142 includes a fuser status register one embodimentof which is illustrated below (TABLE 2) as a 32-bit wide register havingseveral significant bits. The fuser status register is used to indicatereadiness of the fuser controller 142 for a PWM value update. Typically,the firmware clears the Ready bit (R-bit shown in below) withinapproximately 150 ms or a timeout occurs. The firmware optionallyupdates values in a fuser chop interval register and then clears theReady bit. One embodiment of the fuser interval register is alsoillustrated below. If the firmware does not respond within approximately150 ms of ready becoming true (an interrupt is also generated), then atimeout occurs which disables the FSRE output and sets the Timeout Errorbit. The firmware can clear the Timeout Error bit by writing to thisregister.

TABLE 2 Fuser Status Register (FSR) Read/Write 0x010500C4 31 30 29 28 2726 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T R F default XX X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 0 0 F: FSRE(state of the FSRE output for testing, read only) R: Ready for PWM valueupdate (1 = ready) T: Timeout Error (1 = error)

The fuser controller 142 includes the fuser chop interval register oneembodiment of which is illustrated (TABLE 3) below as a 32-bit wideregister. Here, 16-bits are used to indicate a chop interval inmicroseconds (us). The chop interval specifies the basic unit of timeused for the PWM output signal. This value is typically set to ½ of theAC line frequency (e.g. 8333 for 60 Hz). This value allows the triac tobe enabled for quantum intervals of the AC power cycle to provide apredictable RMS (root mean squared) power output for any given PWMwaveform.

TABLE 3 Fuser Chop Interval Register (FCIR) Read/Write 0x010500C8 31 3029 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 43 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I I I I I I I I I I I I I I I Idefault X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0I[15:0]: Chop Interval (in μSec)

The fuser controller 142 includes a fuser PWM register one embodiment ofwhich is illustrated below (TABLE 4) as a 32-bit wide register. Thefuser PWM register defines the FSRE (triac control) output waveform.

TABLE 4 Fuser PWM Register (FPR) Read/Write 0x010500CC 31 30 29 28 27 2625 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 00 0 0 0 0 0 A A A A B B B B C C C C D D D D E E E E F F F F default X XX X X X X X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A[3:0]: HighInterval (first period) B[3:0]: Low Interval (first period) C[3:0]: HighInterval (second period, may be zero) D[3:0]: Low Interval (secondperiod, may be zero) E[3:0]: High Interval (third period, may be zero)F[3:0]: Low Interval (third period, may be zero)

Example PWM values are listed in TABLE 4 below.

TABLE 4 n latency dutycycle register 0 15 0.0% 0x0f0000 7 14 7.1%0x1d0000 8 12 8.3% 0x1b0000 9 11 9.1% 0x1a0000 10 10 10.0% 0x190000 11 911.1% 0x180000 13 15 13.3% 0x111c00 14 14 14.3% 0x111b00 15 13 15.4%0x111a00 17 6 16.7% 0x150000 18 11 18.2% 0x111800 20 5 20.0% 0x140000 2114 21.4% 0x111119 22 9 22.2% 0x111600 23 13 23.1% 0x111118 25 8 25.0%0x151100 27 11 27.3% 0x111116 29 7 28.6% 0x141100 30 10 30.0% 0x15111133 9 33.3% 0x111114 38 8 37.5% 0x131111 40 5 40.0% 0x121100 43 7 42.9%0x121111 50 6 50.0% 0x111111 57 7 57.1% 0x111121 60 5 60.0% 0x211100 638 62.5% 0x311111 67 6 66.7% 0x311100 70 10 70.0% 0x511111 71 7 71.4%0x114100 73 11 72.7% 0x611111 75 8 75.0% 0x511100 77 13 76.9% 0x81111178 9 77.8% 0x611100 79 14 78.6% 0x911111 80 5 80.0% 0x410000 82 11 81.8%0x811100 83 12 83.3% 0x119100 85 13 84.6% 0xa11100 86 7 85.7% 0x61000087 15 86.7% 0xc11100 88 8 87.5% 0x710000 89 9 88.9% 0x810000 90 10 90.0%0x910000 91 11 90.9% 0xa10000 92 12 91.7% 0xb10000 93 14 92.9% 0xd10000100 15 100.0% 0xf00000Stepper Motor Controller 144

The stepper motor controller 144 is used to control a stepper motor (anelectro-mechanical component 50 of the printer 100). An interrupt isgenerated when the stepper motor controller 144 is ready for a newstepper period value. The interrupt may be used to programmatically rampthe stepper motor up to full speed.

The stepper motor controller 144 includes a stepper motor controlregister one embodiment of which is illustrated (TABLE 5) below as a32-bit wide register. This register controls the functionality of thestepper motor. Winding of the stepper motor are powered when StepperMotor Enable bit is set. Phase outputs of the stepper motor areactivated when Step Enable bit is set. The Update Interval bits specifyhow often an interrupt is generated requesting a period value change(and how often the corresponding Ready bit is set in a stepper motorstatus register). Using the quarter-period setting can result in asmoother ramp.

TABLE 5 Stepper Motor Control Register (SMCR) Read/Write 0x01050040 3130 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 54 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U U SM Default X X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 0 00 U[1:0]: Update Interval 00 = request update on every quarter-period 01= request update on every half-period 1x = request update on everyfull-period S: Step Enable (1 = enabled) M: Stepper Motor Enable (1 =enabled)

The stepper motor controller 144 includes a stepper motor statusregister one embodiment of which is illustrated (TABLE 6) below as a32-bit wide register. In the stepper motor status register, a Ready bitis set when the stepper motor controller 144 is ready for an updatedstepper period (used to ramp the stepper motor up to speed). How oftenthe Ready bit is set depends on the setting of the Update Interval bitsin the stepper motor controller 144. An interrupt is generated when theReady bit is high. To clear the interrupt, the Ready bit is written tozero. Two phase outputs can be observed via this register for testingpurposes.

TABLE 6 Stepper Motor Status Register (SMSR) Read 0x01050048 31 30 29 2827 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 R 0 B Adefault X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 X 0 0 R:Ready for Update (1 = ready for updated stepper period) A: Phase Aoutput loopback (read only, for testing purposes) B: Phase B outputloopback (read only, for testing purposes)

The stepper motor controller 144 includes a stepper motor periodregister one embodiment of which is illustrated below (TABLE 7) as a32-bit wide register. The stepper motor period register specifies thestepper motor period. It is typically set to one quarter of the desiredperiod (in clock cycles).

TABLE 7 Stepper Motor Period Register (SMPR) Read/Write 0x01050044 31 3029 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 43 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q QDefault X X X X X X X X X X X X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Q[19:0]: Quarter Period Value (in clock cycles, 2 < Q < 2²⁰)Laser Scanner Controller 146

The laser scanner controller 146 maintains the proper scan mirrorrotation frequency as a closed-loop feedback system of laser and scanner(both components of the electro-mechanical component 50 of the printer100). The laser scanner controller 146 maintains accurate scan rotation,controls the laser for horizontal synchronization, and defines theprintable region. A Laser Scanner interrupt is generated when the statuschanges (for example, when an error occurs due to a scannermalfunction). FIG. 3 illustrates a timing diagram showing five countvalues—T1, T2, T3, T4, and T5—that are controlled by the laser scannercontroller 146. For example, time period T1 defines the horizontal beamsweep period; periods T2 and T3 define the printable region (enablelaser); and periods T4 and T5 define the synchronization window (lookingfor raw beam detect). Such techniques are known in the art. In FIG. 3,raw beam detect (BDI) signal 160 is raw signal from a horizontal syncoptical sensor. This sensor detects laser beam as it sweeps. PrintWindow162 defines the printable region of each line. BDwindow 164 defines thetime where the laser is forced on (for horizontal beam detection).

The laser scanner controller 146 includes five timing registers to storethese timing values—T1, T2, T3, T4, and T5. One embodiment of theseregisters is illustrated (TABLE 8) below, each as a 32-bit wideregister. These registers specify the desired timing and are configuredbefore enabling the laser scanner motor.

TABLE 8 LaserScanner Timing Register 1 (LTR1) Read/Write 0x01050088LaserScanner Timing Register 2 (LTR2) Read/Write 0x0105008C LaserScannerTiming Register 3 (LTR3) Read/Write 0x01050090 LaserScanner TimingRegister 4 (LTR4) Read/Write 0x01050094 LaserScanner Timing Register 5(LTR5) Read/Write 0x01050098 31 30 29 28 27 26 25 24 23 22 21 20 19 1817 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 V V V V V V V V V V V V V V V V Default X X X X X X X X X X X X X XX X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 V[15:0]: Timing parameter value Thevalues specify the timing for each parameter. The value is the number ofsystem clock cycles (for example, 40 ns per cycle).

The laser scanner controller 146 includes a laser scanner controlregister one embodiment of which is illustrated (TABLE 9) below as a32-bit wide register. This register controls the laser scanner motorclosed-loop feedback. The motor is enabled only after programming thetiming registers discussed above. The minimum correction pulse widthvalue of the laser scanner control register can be used to preventglitches on the adjustment output signals (specifying a minimumadjustment pulse width). The In-lock correction pulse limit, whenenabled, allows only minor corrections (the correction is equal to W,the minimum pulse width) after the scan motor is locked (to improvenoise immunity).

LaserScanner Control Register (LCR) Read/Write 0x01050080 31 30 29 28 2726 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 W W W W W W X X X X X X D E default XX X X X X X X X X X X X X X X X X 0 0 0 0 0 0 X X X X X X 0 0 W[5:0]:Minimum correction pulse width D: In-lock correction pulse width limit(1 = enable maximum pulse width) E: Enable scan motor (1 = enable)

The laser scanner controller 146 includes a laser scanner statusregister one embodiment of which is illustrated below as a 32-bit wideregister. This register indicates the status of the scanner motor speed.An interrupt is generated when this status changes.

LaserScanner Status Register (LSR) Read/Write 0x01050084 31 30 29 28 2726 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 M S L default XX X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 0 0 L Locked(1 = scanner at speed) S: Speed Error (1 = scanner malfunction - fellout of lock) M: Missing BD error (1 = scanner malfunction - no BD whenexpected) The locked bit is read-only. The error bits must manuallycleared by writing them to zero.Voltage Controller 148

Transformers and diode/capacitor voltage doublers are used to generatethe high-voltage supplies as parts of the electro-mechanical component50 of the printer 100. Switching waveforms to generate these voltagesare provided by the voltage controller 148. Five programmable outputsare provided to generate up to five high voltages for theelectrophotographic process.

An interrupt is generated on each of the specified output state changes(when enabled). Values for these programmable output signals are storedin five high voltage registers of the voltage controller 148. Oneembodiment of these high voltage registers are illustrated below.

High Voltage Register 0 (HVR0) Read/Write 0x01050140 High VoltageRegister 1 (HVR1) Read/Write 0x01050144 High Voltage Register 2 (HVR2)Read/Write 0x01050148 High Voltage Register 3 (HVR3) Read/Write0x0105014C High Voltage Register 4 (HVR4) Read/Write 0x01050150 31 30 2928 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 21 0 E Q U U H H H H H H H H H H H H I I D D L L L L L L L L L L L LDefault 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0L[11:0]: Low period D[1:0]: Low period units 00 = clocks 10 = 10 μSec 01= μSec 11 = 100 μSec I[1:0]: Interrupt Mode 00 = none 10 = positive edge01 = falling edge 11 = both edges H[11:0]: High period U[1:0]: Highperiod units 00 = clocks 10 = 10 μSec 01 = μSec 11 = 100 μSec Q:Quiescent state (when disabled) E: Enable (1 = enabled)General Purpose Input and Output (GPIO) 150

The GPIO 150 provides an interface to the sensors and paper picksolenoid as well as to the print engine. Further, in some embodiments,it also provides a gating signal for the beam detect to support thelegacy video hardware. A GPIO interrupt is generated when the value ofmechanism sensor register changes. The GPIO 150 includes the mechanismsensor register one embodiment of which is illustrated below as a 32-bitwide register. This register is used to determine the value of themechanism sensors. For example, sensor value Debounce value is providedin hardware to provide stable read values for status. Optical sensors(nPaperIn and nPaperOut) received 512 microsecond (us) of debounce. Thedoor open switch (nDoorOpen) receives 32 ms of debounce. A GPIOinterrupt is generated when the value of this register changes.

Mechanism Sensor Register (MSR) Read 0x01050100 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D P I Default X X X X XX X X X X X X X X X X X X X X X X X X X X X X X X X X D: Door open (1 =door open) P: Paper output sensor (1 = paper present in output path) I:paper input sensor (1 = paper present in input path)

The GPIO 150 includes a mechanism control register one embodiment ofwhich is illustrated below as a 32-bit wide register. This register isused to control the paper pick solenoid.

Mechanism Control Register (MCR) Read/Write 0x01050104 31 30 29 28 27 2625 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 S Default X XX X X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 S: paperpick solenoid (1 = solenoid active)

The GPIO 150 includes a beam detect register one embodiment of which isillustrated below as a 32-bit wide register. This register is used toenable a beam detect output (BDO) signal, a signal from a videocontroller. This is provided in some embodiments for legacy hardwarecompatibility. The firmware enables the beam detect output signal afterthe top of a page is detected. This register may not be required for allembodiments.

Beam Detect Register (BDR) Read/Write 0x01050108 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E Default X X X X XX X X X X X X X X X X X X X X X X X X X X X X X X X 0 E: Beam detectEnable (1 = enabled)Interrupt Controller 152

The interrupt controller 152 generates an interrupt at 10 ms intervalsto enable a top-level periodic servicing routine. For example, the fusercontroller 142 has a real-time interrupt requirement—for safety reasons,the controller disables itself if not serviced within about 150 ms. Forperformance reasons, the stepper motor controller 144 is servicedquickly during ramp up. The paper input sensor (GPIO) needs to bedetected quickly, for example less than one ms to determine thetop-of-page accurately.

Here is a brief description of the interrupt sources:

Page Timer—

-   -   Interrupt when reacting trigger count (pulse)

Time—

-   -   Interrupt every 10 ms (pulse)

EP Voltage—

-   -   Interrupt on selected PWM output edges (pulse)

GPIO—

-   -   Interrupt when sensor status value changes (pulse)

Fuser—

-   -   Interrupt when ready for next PWM code

LaserScanner—

-   -   Interrupt on status change

A2D—

-   -   Interrupt each time all A-to-D values are updated (pulse)

Stepper Motor—

-   -   Interrupt when ready for new period value (quarter/half/full        period)

The interrupt controller 152 includes an interrupt enable register oneembodiment of which is illustrated below as a 32-bit wide register. Whencorresponding bit is set high in the interrupt enable register, theinterrupt will be enabled (passed to the top-level interruptcontroller); otherwise the interrupt is masked. Even when masked, aninterrupt condition may be seen in an interrupt pending register alsoillustrated below.

Interrupt Enable Register (IER) Read/Write 0x010501C4 31 30 29 28 27 2625 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 H G F E D C B A default X XX X X X X X X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 A: PageTimer Interrupt Enable B: Time Interrupt Enable C: EP Voltage InterruptEnable D: GPIO Interrupt Enable E: Fuser Interrupt Enable F:LaserScanner Interrupt Enable G: A2D Interrupt Enable H: Stepper MotorInterrupt Enable

The interrupt controller 152 includes the interrupt pending register oneembodiment of which is illustrated below as a 32-bit wide register. Whenan interrupt is received by the interrupt controller 152, a pending bitis set and remains set until cleared by writing the interruptacknowledge register illustrated below. Firmware can set the interruptby writing to the interrupt force register also illustrated below. Forinterrupt sources that are enabled in the interrupt enable register, aninterrupt will be passed to the top-level interrupt controller when thecorresponding bit is set in the interrupt pending register.

Interrupt Pending Register (IPR) Read 0x010501C0 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 H G F E D C B A Default X X X X XX X X X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 A: Page TimerInterrupt Enable B: Time Interrupt Enable C: EP Voltage Interrupt EnableD: GPIO Interrupt Enable E: Fuser Interrupt Enable F: LaserScannerInterrupt Enable G: A2D Interrupt Enable H: Stepper Motor InterruptEnable

The interrupt controller 152 includes the interrupt acknowledge registerone embodiment of which is illustrated below as a 32-bit wide register.When an interrupt is received by interrupt controller 152, the pendingbit is set and remains set until cleared by writing the interruptacknowledge register. To clear a pending interrupt, the correspondingbit is set high in this register (there is no need to write it backlow). Note that for level interrupts, writes to this register areineffective if the interrupting source is still present; rather, theinterrupting source should be cleared first.

Interrupt Acknowledge Register (IAR) Write 0x010501C8 31 30 29 28 27 2625 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 H G F E D C B A default X XX X X X X X X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 A: PageTimer Interrupt Enable B: Time Interrupt Enable C: EP Voltage InterruptEnable D: GPIO Interrupt Enable E: Fuser Interrupt Enable F:LaserScanner Interrupt Enable G: A2D Interrupt Enable H: Stepper MotorInterrupt Enable

The interrupt controller 152 includes the interrupt force register oneembodiment of which is illustrated below as a 32-bit wide register. Thisregister enables firmware to set individual interrupts. After writing tothis register, the corresponding bits are set in the interrupt pendingregister, and the interrupt is passed to the top-level interruptcontroller, if enabled. There is no need to clear the bits back to zero.

Interrupt Force Register (IFR) Write 0x010501CC 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 H G F E D C B A default X X X X XX X X X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 A: Page TimerInterrupt Enable B: Time Interrupt Enable C: EP Voltage Interrupt EnableD: GPIO Interrupt Enable E: Fuser Interrupt Enable F: LaserScannerInterrupt Enable G: A2D Interrupt Enable H: Stepper Motor InterruptEnablePage Timer 154

The page timer 154 is a 16-bit counter with one ms resolution. It can beused as a general purpose timer and is intended for keeping track of thepage control timing sequence. A page timer interrupt is generated, ifenabled, when the counter reaches a predetermined count. The page timer154 includes a timer control register one embodiment of which isillustrated below as a 32-bit wide register. This register enables thepage timer 154, a page timer interrupt, or both. The register is alsoused to specify a trigger count (an interrupt is generated, if enabled,when the trigger count is reached). The page timer 154 is reset to zerowhen the counter is disabled (it can also be cleared by writing directlyto the count register).

Timer Control Register (TCR) Read 0x01050180 31 30 29 28 27 26 25 24 2322 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 E I 0 0 0 0 00 0 0 0 0 0 0 0 0 T T T T T T T T T T T T T T T T default 0 0 X X X X XX X X X X X X X X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E: Counter Enable (1 =enable counter) I: Interrupt enable (1 = enable interrupt) T[15:0]:Trigger count for interrupt

The page timer 154 includes a timer elaptedtime register one embodimentof which is illustrated below as a 32-bit wide register. This registerindicates how many milliseconds have elapsed since the counter wasreset. The count can also be written to initialize a value, if desired.The counter increments once every millisecond and rolls over afterreaching the maximum count. The ElapsedTime is cleared to zero if thetimer is disabled in the timer control register.

Timer ElapsedTime Register (TER) Read 0x01050184 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 C C C C C C C C C C C C C C C C Default X X X X XX X X X X X X X X X X X X X X X X X X 0 0 0 0 0 0 0 0 C[15:0]: Count (inmilliseconds)Analog to Digital Converter Interface 156

The analog to digital (AD) converter interface 156 provides an interfaceto an external 4-channel serial AD converter such as, for example,National model ADC0834. When the AD interface 156 is enabled, theinterface 156 continually reads sampled values from the AD converter andupdates each of the registers of the controller circuits 140 toeliminate latency and overhead of manual reads. AD interrupts aregenerated when all channel values have been updated (regardless ofwhether or not the values actually changed). The AD channels are used tomeasure items such as fuser temperature, electrophotography voltages,etc.

The analog to digital (AD, A2D) converter interface 156 includes an ADenable register one embodiment of which is illustrated below as a 32-bitwide register. This register is set to enable or disable theanalog-to-digital interface 156. When enabled, four values may be readfrom the A2D data registers also illustrated below.

A2D Enable Register (AER) Read/Write 0x01050010 31 30 29 28 27 26 25 2423 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E Default X X X X XX X X X X X X X X X X X X X X X X X X X X X X X X X 0 E: Enable A-to-Dsampling (1 = enabled)

The analog to digital (AD, A2D) converter interface 156 includes aplurality of AD data registers one embodiment of which are illustratedbelow. These registers are continually updated from an external A-to-Dconverter when the controller circuits 140 are enabled via the A2Denable register. The AD converter interface 156 can include the ADcircuits integrated within the ASIC 130.

A2D Data Register 0 (ADR0) Read 0x0105000  A2D Data Register 1 (ADR1)Read 0x01050004 A2D Data Register 2 (ADR2) Read 0x01050008 A2D DataRegister 3 (ADR3) Read 0x0105000C 31 30 29 28 27 26 25 24 23 22 21 20 1918 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 D D D D D D D D Default X X X X X X X X X X X X XX X X X X X X X X X X X X X X X X X X D[7:0]: 8-bit A-to-D conversionresults for each channel The values are only updated when the A-to-Dconverter is enabled in the A2D Enable Register.The Flash Memory 139

Continuing to refer to FIGS. 2A and 2B, the combination enginecontroller board 130 includes memory 139 such as flash-type memory forstorage of instructions for the combined controller ASIC 132 to execute.These instructions, when executed by the combined controller ASIC 132,causes the combined controller ASIC 132 to process the received data 22such as to format the received data 22 for printing. Further, theinstructions, when executed by the combined controller ASIC 132, causethe combined controller ASIC 132 to control the operations of theelectro-mechanical components 50 via its controller circuits 140. Theseinstructions include, for example, interrupt service routines thatexecute on various interrupts of the printer 100. Sample interruptservice routines are appended to this document as computer source codeon CD-ROM media.

The interrupt service routines provide real-time servicing for the fusertemperature control, the main paper drive motor speed (ramp-up andramp-down), and the laser beam scanner. Because the routines areinterrupt-based, the overhead to system CPU is minimal. The source codealso includes functions for manipulating the other parts of themechanism that do not require real-time control.

The flash memory 139 includes various parameters necessary for efficientoperation of the printer 100. These parameters can include, for exampleonly, fuser temperature settings, print engine timing, and variousvoltage control values.

From the foregoing, it will be appreciated that the present invention isnovel and offers advantages over the current art. Although a specificembodiment of the invention is described and illustrated above, theinvention is not to be limited to the specific forms or arrangements ofparts so described and illustrated. The invention is limited by theclaims that follow. Only those claims specifically reciting “means for”or “step for” should be construed in the manner required under the sixthparagraph of 35 U.S.C. section 112.

1. An integrated circuit for controlling operation of a printer togenerate a printed page, the integrated circuit comprising: a processorcore to format data into printer formatted data; and printer controlcircuitry in communication with the processor core, wherein theprocessor core and the printer control circuitry are connected to abackplane in the integrated circuit, wherein the processor core furthercontrols the printer control circuitry to generate the printed page inaccordance with the printer formatted data, and wherein the printercontrol circuitry comprises a fuser controller, a laser scannercontroller, and an interrupt controller.
 2. The integrated circuit ofclaim 1, wherein the printer control circuitry communicates withelectro-mechanical components of the printer to generate the printedpage in accordance with the printer formatted data.
 3. The integratedcircuit of claim 2, wherein the printer control circuitry comprises arewritable memory location, wherein the rewritable memory locationreceives operating instructions to control electro-mechanical componentsof the printer.
 4. The integrated circuit of claim 3, wherein therewritable memory location comprises a flash memory.
 5. The integratedcircuit of claim 3, wherein the operating instructions comprise aninterrupt service routine programmed to execute on an interrupt of theprinter.
 6. The integrated circuit of claim 3, wherein: the fusercontroller is configured to control operation of a printer fuser; andthe rewritable memory location comprises a memory register to receivefuser operating data associated with the printer fuser.
 7. Theintegrated circuit of claim 6, wherein the fuser operating datacomprises pulse width modulation values for use in controlling atemperature of a heating element in the printer fuser.
 8. The integratedcircuit of claim 1, further comprising an internal bus, wherein theprinter control circuitry communicates with the processor core via theinternal bus.
 9. A printer comprising the integrated circuit of claim 1.10. The printer of claim 9, wherein the printer comprises a laserprinter.
 11. A method comprising: receiving data relating to a print jobat an integrated circuit; processing the data in a processor core of theintegrated circuit; communicating the data processed in the processingcore with a controller circuit in the integrated circuit, wherein thecontroller circuit includes a fuser controller, a laser scannercontroller, an interrupt controller, and a rewritable memory thatreceives operating instructions to control electro-mechanical componentsof a printer and which includes a memory register to receive fuseroperating data associated with a printer fuser; and executing aplurality of interrupt-based service routines to controlelectro-mechanical components associated with a printer, wherein thedata processing and control of the electro-mechanical components areexclusively executed by the integrated circuit.
 12. The method of claim11, wherein the printer comprises a laser printer.
 13. The method ofclaim 11, wherein the fuser operating data comprises pulse widthmodulation values for use in controlling a temperature of a heatingelement in the printer fuser.
 14. The method of claim 11, wherein theprocessor core and the control circuit are connected to a backplane inthe integrated circuit.
 15. The method of claim 11, further comprisingcommunicating with electro-mechanical components to generate a printedpage in accordance with printer formatted data.
 16. An integratedcircuit configured to control operation of a printer to generate aprinted page, the integrated circuit comprising: printer controlcircuitry in communication with the processor core; and a processor corein communication with the printer control circuitry, the processor coreconfigured to: format data into printer formatted data; and control theprinter control circuitry to generate the printed page in accordancewith the printer formatted data, wherein the printer control circuitrycomprises a fuser controller, a laser scanner controller, an interruptcontroller, and a rewritable memory, and wherein the rewritable memoryis configured to receive operating instructions to controlelectro-mechanical components of the printer and includes a memoryregister to receive fuser operating data associated with a printerfuser.